Final answer:
The question pertains to calculating concentrations of species in a solution with Cd and Al after the addition of NaOH, using simplifying approximations and equilibrium conditions. A complete answer would require additional information such as reaction stoichiometry and equilibrium constants.
Step-by-step explanation:
The student appears to be asking how to calculate the concentrations of various species in solution at a certain temperature and with given initial concentrations of cadmium (Cd) and aluminum (Al). More context would be needed to provide a complete solution, including the stoichiometry of the reactions involved and the relevant equilibrium constants.
However, directing the focus to the part of the question involving the addition of NaOH to a solution containing Cd2+, we would begin by calculating the change in concentration that occurs when a strong base like NaOH is added to a Cd2+ solution. Considering that NaOH will react with Cd2+ to form Cd(OH)2, a precipitate, we can calculate the concentration of Cd2+ that would remain in equilibrium with Cd(OH)2 in a 0.04 M OH− solution by using the relevant solubility product (Ksp) for Cd(OH)2.
When simplifying approximations are appropriate, initial concentration values are used to calculate the stoichiometric precipitation, before applying the equilibrium conditions to find the residual concentration of Cd2+.